Spark plug



Dec. 15, 1936. F. STEMMELER SPARK PLUG Filed Jan. 25, 1936 and 5 W A "omega 5 Patented Dec. 15, 1936 UNITED STATES PATENT OFFICE 1 Claim.

My invention relates generally to spark plugs, and particularly to a spark plug having novel construction and arrangement and wherein the spark gap extends circumferentially around the sparking end of theplug, and which spark gap is permanently adjusted, and an important object of the invention is to provide a spark plug or the character indicated above in which the burning of spark points is eliminated and the necessity for frequent re-setting thereof eliminated.

Another important object of the invention is to provide in a spark plug of the character indicated above means for efiectively cooling the spark plug, the spark plug being capable of being very easily taken apart and cleaned.

Other important objects of my invention will be apparent from a reading of the following description in connection with the drawing, wherein for purposes of illustration I have shown a preferred embodiment of my invention.

In the drawing:

Figure 1 is a vertical transverse sectional view taken through the embodiment,

Figure 2 is a horizontal sectional view taken through Figure 1 approximately on the line 2-2 and looking downwardly in the direction of the arrows.

Figure 3 is a transverse vertical sectional view showing the core assembly by itself.

Referring in detail to the drawing, the numeral 5 generally designates the spark plug shell which is substantially conventional in general contour and has threaded therein the clamping gland 6 which clamps the porcelain core "I in place. A

In the lower part of the shell 5 are radial openings 8 which communicate with the interior of the shell 5 and act as ducts for cooling air to reach the vertically spaced circumferential copper cooling fins 9 which are superposed on the 1 upper end of the shell electrode III which is fitted The lower edge ll of the electrode shell H) ex-.

tends slightly below the lower edge of the spark plug shell portion i1 and into the aperture of the rounded screw I8 which is circumferentially formed in the lower edge portion of the core and defines the annular shoulder IS on the lower extremity of the core. The exterior of the bore above the electrode shell I0 is laterally expanded as indicated by the numeral 20 so as to define the tapered shoulder 2| on which lies the compressible gasket 22 which is engaged forcibly by the lower end of the gland 6 for forcing the core in place in the shell. The bore of the spark hole engaging portion 15 of the shell is conformably tapered with respect to the electrode shell in so that a jam fit is caused by setting in the flange 6 against the shoulder on the core I.

A central electrode which is generally designated 23 comprises the upper threaded binding post'portion 24 on which the binding post nut 25 is disposed and below this the annular portion 26 which overlies the top of the core I, the body portion 21 which is slightly concentrically spaced from the sides of the bore portion l2 and which has on its lower end the threaded part 28 which engages the threaded portion I3 of the bore of the core. The lower end of the electrode 23 terminates in a threaded socket located above the reduced smooth bore portion H of the core and in this is threaded the shank 29 which is arranged concentrically spaced from the sides of the smooth bore portion l4 and has on its lower end the head 30 provided with the screw slot 3i in its lower end enabling application of a screwdriver thereto. I

The head has the upwardly extending annular flange 32 which is of the same circular size as the lower edge ll of the electrode shell ill and is spaced at the proper sparking distance therefrom. The annulus 32 surrounds the shoulder IS on the lower end or terminal of the core. Between the terminal of the core and. the upper face of the head 30 is the copper washer 33 which acts as a shim for properly spacing the annular sparking rings. Should the rings become worn and require cutting down, the shim may be removed to procure again the proper sparking space therebetween.

It is believed obvious that the spark plug may be entirely disassembled by simply removing the clamp 6 and the shank equipped head 30 and that assembling is equally simple.

It will also be obvious that circulation of air takes place through the radial openings 8 in the shell to the cooling fins 9 surrounding the electrode shell 10, so as to keep the electrode shell I0 66 comparatively cool and prevent burning and pitting of the ring sparkling member thereof. A

new sparking head 30 may be put into place sim- 10 materials, and in the structure and arrangement of the parts, within the spirit of the invention and the scope of the subjoined claim.

What is claimed is:

A spark plug comnrislnsa an insulated core of' tubular form, a spark plug shell surrounding the core and engageable with a spark plug opening in a cylinder head or the like, a gland engaging the shell and the core and holding the core in the shell, a central electrode located in the bore of the core, an outside electrode in the form of a tube surrounding a lower portion of the core, an air chamber between the walls of the shell and the tube and cooling fins ciroumposed on a portion of the tube and positioned in said chamber, said shell having radial openings immediately adjacent the fins for admitting air to the chamber.

FRED STEMMELER. 

